helix Antenna Theory Regular
Joined: 29 Jan 2015 Posts: 64
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Posted: Wed Aug 19, 2015 5:07 pm Post subject: |
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Let me suggest some ideas that specifically have to do with electrically small antennas:
1) Active antenna tuning. This is a hot area for cellular handsets. There are a variety of technologies that can provide variable reactances (mostly capacitive, e.g., Peregrine DCT devices) which can potentially prevent detuning when a handset is placed in different environments. Advantages, disadvantages, and optimality of various combinations of:
1) tuning network topologies,
2) de-tuning sensing techniques,
3) variable reactance devices,
4) different types of antennas, and
5) types of detuning environments
is an area of active research.
2) Non-Foster matching. I think there is some controversy whether it's useful (actually improves SNR in a receiver). A paper I saw concluded that it was indeed useful, however, the authors used an 8dB NF receiver to reach this conclusion (which leaves a lot of room -- about 7dB -- for suspicion). Apparently NFM can be used in transmit-mode as well.
3) Magnetic materials. There is some interesting work dealing with magnetic, rather than dielectric, loading of electrically small antennas. The overall advantages and disadvantages are unclear.
As you can see, all these topics involve something other than pure antennas (matching, electronics or materials). E&M is very old field, and it seems most pure antenna topics have been investigated thoroughly for decades. |
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